Abstract
Xenoturbellida is a group of benthic marine invertebrates with a very simple bilaterian body plan. Together with Acoelomorpha, it constitutes the clade Xenacoelomorpha, recently interpreted as a sister group to all other extant bilaterians (=Nephrozoa). Therefore, it occupies an important phylogenetic position for studies on origins and evolution of Bilateria. However, due to a number of reasons, developmental and reproductive studies on Xenoturbella have been scarce. In this chapter, I will summarize what is known concerning the reproduction and development of Xenoturbellida, including information from five species that were recently discovered. Gonads are absent in xenoturbellids, and gametes are found in various parts of the body. The gametes are released through ruptures of the body wall, and therefore, the fertilization is presumably external. After holoblastic radial cleavage, embryos hatch as free-swimming hatchlings with uniform ciliation over the surface. Apical tuft forms later in development, and 5 days after hatching, the larvae begin to settle on the substrate. Comparison with the other marine invertebrate larvae suggests that the morphologically simple swimming larvae described in Xenoturbella represent an ancestral larval type of all metazoans and bilaterians.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Achatz JG, Chiodin M, Salvenmoser W, Tyler S, Martinez P (2013) The Acoela: on their kind and kinships, especially with nemertodermatids and xenoturbellids (Bilateria incertae sedis). Org Divers Evol 13:267–286
Cannon JT, Vellutini BC, Smith J III, Ronquist F, Jondelius U, Hejnol A (2016) Xenacoelomorpha is the sister group to Nephrozoa. Nature 530:89–93
Deheyn D, Watson NA, Jangoux M (1998) Symbioses in Amphipholis squamata (Echinodermata, Ophiuroidea, Amphiuridae): geographical variation of infestation and effect of symbionts on the host’s light production. Int J Parasitol 28:1413–1424
Gehrke AR, Srivastava M (2016) Neoblasts and the evolution of whole-body regeneration. Curr Opin Genet Dev 40:131–137
Hauszprunar G (2016) Review of data for a morphological look on Xenacoelomorpha (Bilateria incertae sedis). Org Divers Evol 16:363–389
Hejnol A (2015) Acoelomorpha and Xenoturbellida. In: Wanninger A (ed) Evolutionary developmental biology of invertebrates, vol 1. Springer, Wien, pp 203–214
Hejnol A, Pang K (2016) Xenacoelomorpha’s significance for understanding bilaterian evolution. Curr Opin Genet Dev 39:48–54
Hejnol A, Obst M, Stamatakis A, Ott M, Rouse GW, Edgecombe GD, Martinez P, Baguna J, Bailly X, Jondelius U, Wiens M, Muller WEG, Seaver E, Wheeler WC, Martindale MQ, Giribet G, Dunn CW (2009) Assessing the root of bilaterian animals with scalable phylogenomic methods. Proc R Soc Biol Sci B 276:4261–4270
Jondelius U, Wallberg A, Hooge M, Raikova OI (2011) How the worm got its pharynx: phylogeny, classification and Bayesian assessment of character evolution in Acoela. Syst Biol 60:845–871
Martín-Durán JM, Pang K, Børve A, Lê HS, Furu A, Cannon JT, Jondelius U, Hejnol A (2018) Convergent evolution of bilaterian nerve cords. Nature 553:45–50
Nakano H (2015) What is Xenoturbella? Zool Lett 1:22
Nakano H, Miyazawa H (2019) A new species of Orthonectida that parasitizes Xenoturbella bocki: implications for studies on Xenoturbella. Biol Bull 236:66–73
Nakano H, Lundin K, Bourlat SJ, Telford MJ, Funch P, Nyengaard JR, Obst M, Thorndyke MC (2013) Xenoturbella bocki exhibits direct development with similarities to Acoelomorpha. Nat Commun 4:1537
Nakano H, Miyazawa H, Maeno A, Shiroishi T, Kakui K, Koyanagi R, Kanda M, Satoh N, Omori A, Kohtsuka H (2017) A new species of Xenoturbella from the western Pacific Ocean and the evolution of Xenoturbella. BMC Evol Biol 17:245
Nakano H, Miyazawa H, Maeno A, Shiroishi T, Kakui K, Koyanagi R, Kanda M, Satoh N, Omori A, Kohtsuka H (2018) Correction to: a new species of Xenoturbella from the western Pacific Ocean and the evolution of Xenoturbella. BMC Evol Biol 18:83
Obst M, Nakano H, Bourlat SJ, Thorndyke MC, Telford MJ, Nyengaard JR, Funch P (2011) Spermatozoon ultrastructure of Xenoturbella bocki (Westblad 1949). Acta Zool 92:109–115
Philippe H, Brinkmann H, Copley RR, Moroz LL, Nakano H, Poustka AJ, Wallberg A, Peterson KJ, Telford MJ (2011) Acoelomorph flatworms are deuterostomes related to Xenoturbella. Nature 470:255–258
Raikova O, Reuter M, Jondelius U, Gustafsson M (2000) An immunocytochemical and ultrastructural study of the nervous and muscular systems of Xenoturbella westbladi (Bilateria inc. sed.). Zoomorphology 120:107–118
Robertson HE, Lapraz F, Egger B, Telford MJ, Schiffer PH (2017) The mitochondrial genomes of the acoelomorph worms Paratomella rubra, Isodiametra pulchra and Archaphanostoma ylvae. Sci Rep 7:1847
Rouse GW, Wilson NG, Carvajal JI, Vrijenhoek RC (2016) New deep-sea species of Xenoturbella and the position of Xenacoelomorpha. Nature 530:94–97
Ruiz-Trillo I, Paps J (2016) Acoelomorpha; earliest branching bilaterians or deuterostomes? Org Divers Evol 16:391–399
Sikes JM, Bely AE (2008) Radical modification of the A-P axis and the evolution of asexual reproduction in Convolutriloba acoels. Evol Dev 10:619–631
Stach T, Dupont S, Israelsson O, Fauville G, Nakano H, Kånneby T, Thorndyke M (2005) Nerve cells of Xenoturbella bocki (phylum uncertain) and Harrimania kupfferi (Enteropneusta) are positively immunoreactive to antibodies raised against echinoderm neuropeptides. J Mar Biol Assoc UK 85:1519–1524
Westblad E (1949) Xenoturbella bocki n.g, n.sp. a peculiar, primitive turbellarian type. Ark Zool 1:3–29
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2019 Springer Nature Switzerland AG
About this chapter
Cite this chapter
Nakano, H. (2019). Development of Xenoturbellida. In: Tworzydlo, W., Bilinski, S. (eds) Evo-Devo: Non-model Species in Cell and Developmental Biology. Results and Problems in Cell Differentiation, vol 68. Springer, Cham. https://doi.org/10.1007/978-3-030-23459-1_11
Download citation
DOI: https://doi.org/10.1007/978-3-030-23459-1_11
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-23458-4
Online ISBN: 978-3-030-23459-1
eBook Packages: Biomedical and Life SciencesBiomedical and Life Sciences (R0)